Process for producing low foaming latexes of interpolymers containing vinyl chloride and ethylene

Claim 1

In the emulsion-polymerization at superatmospheric pressure of an interpolymer comprising vinyl chloride and ethylene, an improvement which provides a stable latex product that remains mechanically stable during and after release of said pressure, said improvement comprising the sequential steps of a. maintaining ethylene pressure at a level between about 50 and 15,000 psi on an aqueous composition containing i. a seed latex made by free-radical initiated emulsion copolymerization of ethylenically unsaturated monomers, ii. an anionic surfactant in amount at least 0.005 percent and not exceeding 0.4 percent based on weight of comonomer charged, and iii. a free-radical initiator system maintained at a level sufficient to effect emulsion polymerization while b. adding gradually, over a period of not less than six hours, a comonomer charge including a major proportion of vinyl chloride.

Claim 11

A method of preparing by emulsion polymerization a stable latex of a terpolymer of vinyl chloride, vinyl acetate and ethylene which comprises maintaining ethylene pressure at between about 500 psi and 3,000 psi on an aqueous composition at a temperature between about 50*C and 85*C, said aqueous composition containing a seed latex and an anionic surfactant in an amount between about 0.005 percent and about 0.4 percent based on total weight of vinyl chloride and vinyl acetate added; adding gradually thereto over a period of between about 6 and 24 hours an aqueous solution of a water-soluble alkali metal persulfate or peroxydiphosphate to effect polymerization while simultaneously adding over the same period both vinyl chloride and vinyl acetate in the weight proportions between about 51/49 and 99/1.

Claim 12

A method of preparing by emulsion polymerization a stable latex of a terpolymer of vinyl chloride, vinyl acetate and ethylene which comprises maintaining ethylene pressure at between about 500 psi and 3,000 psi on an aqueous composition at a temperature between about 50*C and 85*C, said aqueous composition containing a seed latex and an anionic surfactant in an amount between about 0.005 percent and about 0.4 percent based on total weight of vinyl chloride and vinyl acetate added; adding gradually thereto over a period of between about 6 and 24 hours an aqueous solution of a water-soluble alkali metal persulfate or peroxydiphosphate to effect polymerization while simultaneously adding over the same period both vinyl chloride and vinyl acetate in the weight proportions between about 51/49 and 99/1.

Claim 13

A method of preparing by emulsion polymerization a latex containing between about 40 percent and 66 percent solids of a vinyl chloride/ethylene copolymer comprising about 17-20 percent by weight ethylene, said method comprising the steps of a. maintaining substantially constant ethylene pressure at between about 1,200 and 1,500 psi on an aqueous composition at a temperature of between about 55*C and 70*C, said composition comprising between about 0.5 percent and 3.0 percent of a polyvinyl chloride or poly (2-ethyl hexyl acrylate) seed latex and between about 0.005% and about 0.4 percent of an anionic surfactant, b. adding gradually thereto at a substantially constant rate, over a period of between about 12-16 hours, an aqueous solution of a persulfate or peroxydiphosphate initiator, in an amount between about 0.2 percent and 2 percent based on weight of the aqueous composition, to effect polymerization while c. simultaneously adding gradually over the same period an amount of vinyl chloride in about 5-20 percent excess over the theoretical amount needed to obtain the expected solids and d. maintaining the polymerizing system at 55*-70*C until the required solids is obtained.

Claim 14

A method of preparing by emulsion polymerization a latex containing between about 40 percent and 66 percent solids of a vinyl chloride/ethylene copolymer comprising about 17-20 percent by weight ethylene, said method comprising the steps of a. maintaining substantially constant ethylene pressure at between about 1,200 and 1,500 psi on an aqueous composition at a temperature of between about 55*C and 70*C, said composition comprising between about 0.5 percent and 3.0 percent of a polyvinyl chloride or poly (2-ethyl hexyl acrylate) seed latex and between about 0.005% and about 0.4 percent of an anionic surfactant, b. adding gradually thereto at a substantially constant rate, over a period of between about 12-16 hours, an aqueous solution of a persulfate or peroxydiphosphate initiator, in an amount between about 0.2 percent and 2 percent based on weight of the aqueous composition, to effect polymerization while c. simultaneously adding gradually over the same period an amount of vinyl chloride in about 5-20 percent excess over the theoretical amount needed to obtain the expected solids and d. maintaining the polymerizing system at 55*-70*C until the required solids is obtained.